Repair clamps are used in the placement of pipes or for connecting the ends of pipes axially. Such clamps generally have a cylindrical body or band which encircles the subject pipe or pipe ends. Two opposed lugs are attached to the opposed edges of the cylindrically-shaped band, and the lugs are drawn towards each other by tightening bolts or fasteners. This reduces the effective internal diameter of the band, which in turn compresses an elastomeric sheet gasket that is typically placed between the band and the subject pipe. Compressing the gasket sheet seals the gasket to the pipe. To bridge the gap that is formed between the ends of the band, a spanner or bridge plate molded into or placed onto the outer surface of the gasket is employed to provide gasket compression across the gap. The spanner plate fits on the outer surface of the elastomeric sheet gasket and is compressed radially inward by the lugs along the opposed edges of the cylindrical band.
The range of diameters of piping for which a repair clamp may be used is typically fairly limited. For example, at present pipeline repair clamps have a range of about 0.3 to 0.4 inches for the diameter span of pipes that the repair clamp can effectively seal. The linear closure travel necessary for this range is only in the order of 1.20-1.25 inches.